Diatomaceous earth (“DE”) filters are often used to filter the water of swimming pools, spas, water features, etc. DE filters typically include a septum with relatively large pores that DE cannot pass through. Adding a solution of water and DE to the filter can form a cake of DE on the surface of the septum. The addition of the DE to the septum can create a smaller porous structure to improve the filtering capability of the septum. However, contaminants caught in the DE over time can reduce the filtering capability of the septum. As a result, the DE must be removed from the septum and reapplied. Various techniques have been used to remove the DE from the septum. These conventional techniques generally do not remove all the contaminants from the septum, allowing the contaminants to build up and eventually affect the performance of the filter.